Prime rib was a cut of beef that came from the rib area of a cow. Prime rib was similar to steak and was considered a delicacy by many Humans.
While stranded in the desert region of the Torothan homeworld in 2152, a delirious Commander Tucker told Captain Archer that he would like a meal of prime rib, with mashed potatoes and broccoli when he returned to Enterprise NX-01. (ENT: "Desert Crossing")